Manufacture of lusterless rayon



Patented Feb. 28, 1933 omen STATES PATENT OFFICE WILLIALM F. RICHTER, OF APOLLO, PENNSYLVANIA, ASSIGNOR TO CHEIVIIGAL HOLDING CORPORATION, OF APOLLO, PENNSYLVANIA, A CORPORATION OF DELAWARE MANUFACTURE OF LUST'EBLESS BAYON No Drawing.

cose produce fibers having high surface brilliancy, but the trade demand for artificial silks of decreased luster has led to the devel- P opment of the so-called delustered rayon. Various means are used in delustering artificial silk, chiefly by special treatments after spinning, which deaden the luster. The silk produced in this manner, while initially possessing the desired lower luster, gradually increases in luster after being used or washed.

This characteristic is, of course, objectionable. Spinning baths for the direct production of lusterless rayons have not yet been developed and used commercially, because in general such baths are objectionable in that they are of complex composition, and relatively high concentrations of salts are used. Therefore, not only are such baths relatlvely expensive, but the yarn may be weakened through crystallization of salts upon the fibers.

It is among the objects of this invention to provide an improved process of producing lusterless rayon from viscose, in which use is made of baths of simple composition, which are easily used, inexpensive, produce permanently lusterless rayon, and which mlmmize the disadvantages of prior means used for this purpose. 0

The invention is predicated upon my d1scovery that rayon which is permanently lusterless, and which possesses satisfactory physical characteristics, may be produced by precipitating viscose in a bath consisting of sulfuric acid and a soluble nickel salt.

In the practice of this invention viscose is prepared according to any desired procedure, and it is then spun in the usual manner in a bath consistingof sulfuric acid and nickel salt, preferably nickel sulfate in an amount less than the sulfuric acid. Most suitably the bath consists of from about 5 to 7 per cent of sulfuric acid and about 1.5%

0 to 4.5% of nickel sulfate. Especially desir- Application filed October 28 1930. Serial No. 491,815.

able results are obtained through the use of a bath having the following composition;

Sulfuric acid I 6% Nickelsulfateuh; 3%

Mostsuitably the baths provided bythis invention are used at somewhat elevated temeratures, for example, from about 30 C. to 45 C. In the preferred embodiment of the invention the bath is maintained at a temperature from about 35 C. to 40 C.

The artificial silk thus produced is characterized by a soft, substantially lusterless appearance, and it retains this lusterless condition permanently. That is, it is apparently impossible to cause it to assume a higher lus- 'ter by any known procedure. Thus, it does not gain in luster upon repeated washing, or upon prolonged boiling with any ofthe materials to which it may-be subjected in use. Furthermore, the artificial silk produced by; the process provided by this invention possesses all of the physical properties which are characteristic of the normal,- or glassy rayons.

In addition to producing rayon having the characteristics just described, the baths used in the practise of the invention have theadvantage that their composition is exceedingly simple-and their cost is low. Not only is: the salt concentration appreciably lower than that commonly used in rayon spinning baths, but the salt used does not tend to crystallize in the yarn as readily as those commonly used, such as sodium or magnesium sulfates. Therefore, because of these factors weakening of the rayon through crystallization and subsequent washing of the salts is minimized or practically eliminated.

Although nickel salts have been recommended previously for use in rayon precipitating baths, such baths have been of the type which produce rayon of high luster. For such purposes cobalt salts are the full equivalent of nickel salts. In the practice of the present invention such equivalency apparently does not hold.

According to the provisions of the patent statutes,I have explained the principle and mode of operation of my invention, and have described what I now consider to represent its best embodiment. However, I desire to have it understood that, within the scope of the appended claims the invention may be 5 practised otherwise than as specifically illustrated, and described.

I claim: 1. In a process of preparing permanently lusterless artificial fibers from viscose the step comprising precipitating the viscose in a bath consisting of about 5 to 7 per cent of sulfuric acid, and about 1.5 to 4.5 per cent of nickel sulfate.

2. In a process of preparing permanently lusterless artificial fibers from viscose the step comprising precipitating the viscose in a bath consisting of about 6 per cent of sulfuric acid, and about 1.5 to 4;.5 per cent of nickel sulfate, said bath being maintained at a temperature of about vto C. 1

3. In a process of preparing permanently lusterless artificial fibers from viscose the step comprising precipitating the viscose in a bath consisting of about 6 per cent sulfuric acid,

525 and about 3 per cent of nickel sulfate.

In testimony whereof, I sign my name;

WILLIAM F. RICHTER. 

